/ Thesaurus / O Synonyms of os ischii Find synonyms for: Noun1. ischium, ischial bone, os ischii, bone, osusage: one of the three sections of the hipbone; situated below the iliumWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: devout Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language